Pressure line shut-off valve



Feb. 2, 1960 H. T. sEALE PRESSURE LINE SHUT-OFF VALVE Filed April 4, 1955 im Mw 5 .B

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nit-ed States Patent() e n 2,923,576 i t PRESSURE LINE SHUT-oFF VALVE 1 Homer T. Scale, Los Angeles, Calif. Application April 4, 1955S`erial No. 498,871 10 claims. (ci. sos-3o) My invention relates to pressure line shut-ot` valves, that is, to shut-oil valves adapted to close the upstream side of a pressure line should pressure in the down stream side drop below a safe minimum, and included in the objects of my invention are:

First, to provide a shut-off valve which is particularly adapted for use in, but not limited to, tractor-trailer air-brake systems, and which may be incorporated in the trailer line control apparatus disclosed in my previous Patent Number 2,700,435, issued January 25, 1955;

Second, to provide a shut-olf valve which may be so installed in a trailer line control system that, inthe event of either accidental or intentional break in the pressure line lbetween a tractor unit and trailer unit, aire supply is automatically shut oiso as to prevent loss of air pressure in the tractor unit. Third, to provide a shut-off valveof this type which,- when caused to `shut ol a pressure line-must `thereafter be manually reopened. p .V

Fourth, to provide a shut-off valve ofthis type which is arranged for manual as well as automatic operation, whereby the pressure line controlled thereby maybe opened or closed at the will of the operator. A I

Fifth, to provide a, shut-olf valve of this type which permits the normal iluctuations of pressure in the pres-` sure line occasioned by use of the braking system ofthe tractor and trailer soas not to interfere in any manner with the supply of air to the trailer unit or storage of air for brake-application purposes. Sixth, to provide a valve of this type which is notonly particularly dependable in operation but also economical of manufacture, and easily installed and serviced.

With the above and other objects in view, as may appear hereinafter, reference is directed to the accompanying drawings in which:

Figure l is a longitudinal sectional view through 'my pressure line shut-oivalve with the valve shown in its operating position; i

Fig. 2 is a transverse sectional view through Fig. l;

Fig. 3 is a transverse Fig. 1; e t

Fig. 4 is a diagrammatical view of .the pressure shutoff valve, as employed `in the air-brake pressure line between a tractor and a trailer, showing the manner of its installation in an air-brake system with the valveshown in;,its open position; `and e .e p

Fig. 5 is a similar diagrammatical view, showing the Valve inits closed position. e e

My trailer line shut-olf valve includes `a valvebody 1 having a longitudinal bore therethrough which defines amajor chamber `2 at qneend of the valve body, an intermediate lminortchamberf, and an exhaust chant- `ber 4. A valve` seat 5 is formed by theshOuIderlJel tween the minor chamber `3 and theexhaust chamber 4.

sectional view through 3--3 An inlet port 6 intersects the side of the major chamber.

" the valve body 1 in which 2,923,576 Patented Feb. 2, 1960 lCe ber 2.

"lhe exhaust chamber 4 is intersected by Aanexhaust portj 9; 'lh`e end of the valve body 1 having the ex- ..aus t `chamber 4 is provided with laterally directed mounting feet 10 so that the valve may be securedY to the back side of a panel A.

The end of the valve body 1 having'the major chamber 2 is furtherenlarged `andinternally screw threaded toreceive a cap l1 whichclses themajor chamber 2, but clears the major chamber sufficiently to provide communication between the major chamber 2 and the passage 8. The cap 11` is provided with an annular raised seat 12 which confrontsthe major chamber `2 and is equal in diameter to the valve seat 5. A l

The bore of the valve body 1 receivesA avalve plunger 13 which includes a major piston` 14 fitting the major chamber 2 and a minor piston 15 which fits the minor chamber 3. The valve plunger further includes a stem 16 whichrconnects the pistons 14 and 15 and extends intq the exhaust chamber 4. r A` passage 17 extends downwardly through the major piston 14and commu cates with the region between the two pistons. s

The upper side of the major piston 14 is provided with a valve seat 18` which engages the valve seat 12.

The "lower side of `the minor piston 15 is provided wit a valve seat 19 which engages the valve seat 5.

` through the adjacentend of the valve body and screw thread into the polygonal end of the s ternr16. The outer end ot'` the rod` projects through `the panel AV andis` provided with a knobl22. r e

Interposed between the outlet port 7 and the passage 8 is an orifice `disc `23.`

Operation ofjmyshut-otf valve .when employed as a trailer linecontrol valve is 'as rollowlsil i The shut-oil valve is mounted onfthe dashboard of the tractor or otherwise located in a positionaccessible to thedriver. The ,inlet port disconnected to the air supply v1? ofthe tractor and trailer, asshown in the diagrammatical views, Figs...4 and 5. A l

The outlet port"7 is" `connectedftofthe pressure line C which'leads to the trailer. The airsupply line B also communicates` with a foot-operated air valve D which controls the brakes `E of the tractor and is connected through an application line.F to the brakes of the trailer. e l

When the tractor and trailer are connected and the brakes are in operation, the trailer line control valve occupies the position shown in Figs. l and 4. In this position the inlet port 6 is connected to the outlet port 7 throught he major chamber 2 `between the two pistons 14 and 15, passage17, passage 8, and orifice disc 23. By reason` of the passage 17 the pressure on opposite sides of themajorpiston 14 is equal and opposed; that is, there is'no pressure dilerential across the piston 14 to urge it in either direction. However, the upper side of the piston 15 is subjected to the pressure existing in the inlet chamber between `the pistons 14 and `15 and therefore holds the plunger 13 in its lower position, shown in Figs.` 1 and 4. t,

Should the pressure in the pressure line C to the trailer drop below a predetermined value, the pressure above `the major piston 14 isfrelieved lso that sufficient pressure dilerential isestablished across the major piston 14 to raise the plunger 13 in `opposition to the pressure ori top of the piston 15 untilthe valve seat 18 of the major piston 14 closes against the valve seat 12. In doing so, any"residual air pressure inthe pressure line to the trailer exhausts through the minor chamber 3, exhaust chamber 4, and exhaust port 9, as shown in Fig. 5. e l' When the valve is in the position shown in Fig. 5, the pluneertlA may Ybeltloved t imposition Shawls ,infie- 1 and 4 b'y manual pull on the knob 22. -However; the v alve will not stay in thepposition shown inuligsml and `4 ifrvthe pressureY line to the trailerd is open to the atmosphere. If the pressure line to thetrailerfis in; proper condition, the valve will stay in its position shown in Figs. l and 4, as soon as the air supply has built the proper back'pressure in the pressureV line to the trailer so y,as to reestablish pressure on top uof the pistonlfirv. h ,e In the normal'use ofthe air `brakes, particularly under conditions of frequent use,lthe pressure in the pres'- `sure line to the trailer may be permitted to drop a limited amount, and it is undesirable toehave thepresfsure line control valve change fromv'theposition shown in Figs; 1

Aand 4 under sueh conditions.

The ofrece disc ze serv'stpj tjiiiisii al prei-fitte diei-Lil' eri'tial between the regionl above the major p t0n 14 and the pressure line to the'rtrrailenso that a lower-'pressure in theApressureline'iswrequired before the valve plunger 15 ,shiftsits position than would otherwise bel the ease.V By selection of the lproper orifice, the' desired conditions for operation of the valve may be obtained for the particular installation. v Y. Y

e It will thus be observed that the shut-ofi valveautomatically closes to prevent loss of air supply to the' tractor in the event that the pressure line to the trailer should be broken,A but byreason of thel orifice disc 23 it may be arranged to function properly and permit a predetermined lowering of pressure in the pressure line to the trailer. v

In the event that the pressure line is disconnected delibverately,l as in the case of disconnecting the tractor from the trailer, the controlvalve also functions to prevent loss vof .air pressure in the braking system of the tracfor so that the operation of the tractor air brakes are not affected. Upon reconnecting a trailer, it is merelynecess'a'ry to manually reset'the shut-ofi valve.

Having fully described myinventiom'it is'to be understood that Ido not Vwish to be limited to the detailsrherein set forth, but my'invention is of the full scope of the appended'claim's. Y

I claim: I

A tractor-trailer air brake ,system comprising: a source of air pressure carried by the tractor; a pressure maintenance line connectedrto the trailer,"axvalve struc-' ture adapted for installataion/ in said pressure maintenance line, said valve structure including, a valve body structure defining in tandem a major chamber, a minor chamber, an exhaust chamber'lof diminishing area, an intake port communicating with one end of' said major vchamber adjacent said minor chamber and with said aii sburce, an outlet port communicating with said minor chamber and with said pressure maintenance line, a passage frorn said minor chamber to the opposite end of said major chamber remote therefrom, and an exhaust port communicatingv with said exhaust chamber; a plunger having `'major-and minor pistons in saidmajor ,and-'minor chambers and having confronting sides of different area,

said intake port being disposed between said pistons; la first and second valve meansdisposed respectively between the remote ends of said major and minor pistons andthe corresponding ends of said major and minor chambersymeans defining apassage bypassing said ma jor piston and communicating with said outlet port to permit ow from said outlet to said exhaust port; and a manually accessible handle for moving said plunger.

2. A control valve as setgforth in claim l, wherein: a restricted orifice is provided in said outlet to establish a predetermined pressure differential between the air pressure in the maintenance line, connected with said outlet, and the air pressure in the supply line, connected with said inlet, at which said first valve means closes and said second valvekmeans opens. Y l

3. A tractor-trailer air brake system comprising: a source of air pressure carried by the tractor; Va pressure maintenance line connected to the trailer, a valve structure adapted for installation in said pressure maintenance line, said valvestructureincluding, means defining an inlet chamber having a pair of movable walls of different area, said inlet chamber being connected with said source of air pressure; means connecting said walls for movementninl undisongnmeansmdetining with the larger of ,said walls-,a pressure chamber means defining withithe smaller of said-'walls an exhaust chamber; first and secondvalvfes infsaid pressure'chamber" and said exhaust chamber', said valves ineluding movable valveV elements carried by said movable walls; means defining a iiw passage from said inlet to said first valve whereby' said first valve controls flow frornwsaidinlet tosaid pressure chamber; said second valve'controlling flowto said exhaustV chamber; an outlet communicating with" said4 pressure maintenance line and connected with both'saidpressure chamber and exhaust' chamber;` land a manually at': :essiblehandle for moving Vsaid movable w'allsHtol pen and close saidffirst and second valves.

4. A control valve as set'forth inclaim 3,' wherein:4 a restricted orifice is provided' insaid 'outlet to establishf a predetermined pressure differential between air pressure' in said inletcha'mber and the air pressure in said pressure `rnaintenanceA line at which :said first valvev closes' and said second valve opens. e Y i 5. .A` valve structure, comprising: means defining an outlet chambenan inlet chamber, andV anjexhaust chamber, and including a major area movable wall between said inlet andl outlet chambers, and a; minor area movable ,wall betweenV said inlet and' saidexhaust'chambers; saidtmajr and 'minor area walls, having confronting surfacesexpose'd tosaid inlet chamber; an; inlet port for said inlet chamber between" saidv major and minor movable walls;vv an outlet port communicating :with said *outlet chamber; first and second valvesincluding-movable valve' elements carried respectiv`e-lywby' theremo/te" surfaces `of ahdrninorimovablewalls;means defininga flow passage from said`inlet chamberl tosaid outlet chamv be'r throng jsaid first valvejmeansfdefining a discharge passage frozmsaid'outlet portfthrbugh'saidiinlet 'chamber to said exhaust chamber; said major and minor movable walls: afridf` the' movablelelements-ot vsaid first and second valves *being connected together for movement in unison whereby either of said valvesis openedwhenv the other of said valves is closed, the'pres'sure areas of said walls being so proportioned that said first valve tendstoremain open and' said-"second valvetends'to remain closed when the pressuresA at said inlet port and outlet port are substantially equal; andrsaidffirst'valve" closes and' said second valve opensupon drop in pressure at said outlet port; anclrnanually accessible means for moving' said major: and `minor walls vand said movable Vvalve elements. Y 6. Awcontrol valve as set forth in claim 5, wherein: a restrictedorifice'is providedv in said outlet port toestablish apredetermined pressureV differentialV between inlet p brthandolitlet port'at which saidfirst valvecloses and saidsec'ondyalvefopens. e p e T.ln" combination, a pressure line 'an'd la shut-ofi valve, cbrnp means{definingan'inlet'chamber havingfa p'ai `o`fj-fniovablewallsfvof differentl area-said inlet chamb :einig: conneeted with"theu'pstream*sideV of said pressure line; means/connectingsaidwalls for movement in www pressure chamber; means defining with the smaller of said walls an exhaust chamber; tirst and second valves in Said pressure chamber and said exhaust chamber, said valves including movable valve elements carried by said movable walls; means defining a iiow passage from said inlet to said iirst valve whereby said lirst valve controls flow from said inlet to said pressure chamber; said second valve controlling ow to said exhaust chamber; means defining an outlet for connection to the downstream side of said pressure line and passages connecting said outlet with said pressure chamber and said exhaust chamber; the relative areas of said movable walls and said rst and second valves being so proportioned as to cause said first valve to close and said second valve to open, upon pressure drop in the downstream side of said pressure line, thereby to close the upstream side of said pressure line and exhaust the downstream side of said pressure line; and a manually accessible handle for moving said movable walls to open and close said first and second valves.

8. A shut-off valve as set forth in claim 7, wherein: a restricted oriiice is provided in said outlet to establish a predetermined pressure differential between uid pressure in the upstream side of said pressure line and the fluid pressure in the downstream side of said pressure line at which said first valve closes and said second valve opens to effect a Shut-otf of the upstream side of said pressure line and exhaust of the downstream side thereof.

9. A shut-off valve, comprising: means dening an outlet chamber, an inlet chamber, and an exhaust chamber, and including a major area movable wall between said inlet and outlet chambers, and a minor area movable wall between said inlet and said exhaust chambers, said major and minor area movable walls forming opposite sides of said inlet chamber; iirst and second valves in said outlet chamber and exhaust chamber respectively, including movable valve elements carried respectively by the remote sides of said major and minor movable walls exposed to said outlet and exhaust chambers; means denrng a flow passage from said inlet chamber to said outlet chamber through said iirst valve; said second valve forming a discharge means to said exhaust chamber; an inlet port in said inlet chamber disposed between said major and minor movable walls; an outlet port communicating with said outlet chamber and said exhaust chamber; said major and mlnor movable walls and the movable elements of said irst and second valves being connected together for movement in unison, the pressure areas of said walls being so proportioned that said rst valve tends to remain open and said second valve tends to remain closed when the pressures at said inlet port and outlet port are substantially equal, and said first valve closes and said second valve opens upon drop in pressure at said outlet port; and manually accessible means for moving said major and minor walls and said movable valve elements.

10. A control valve as set forth in claim 9, wherein: a restricted orice is provided in said outlet port to establish a predetermined pressure differential between said inlet port and outlet port at which said irst valve closes and said second valve opens.

References Cited in the file of this patent UNITED STATES PATENTS 1,478,669 Mattingly Dec. 25, 1923 1,485,958 Bridgham Mar. 4, 1924 1,563,143 Barlie Nov. 24, 1925 2,238,124 Mathieson Apr. 25, 1941 2,445,544 Trautman July 20, 1948 2,638,108 Williams May 12, 1953 FOREIGN PATENTS 635,751 Great Britain Apr. 19, 1950 

